While the invention is not intended to be so limited, the panel assembly taught herein is particularly useful in lighting and sound applications for theatrical and concert productions, circuses, television studios, movie studios and the like. Lighting and sound equipment require a multitude of connections. In these applications, single conductor connectors are preferred. This is true because cable for multiple conductor connectors is generally of large diameter, heavy, and difficult to maneuver and transport.
When dealing with single conductor connectors, there are several important factors to consider, to prevent damage to the equipment and for safety reasons. First of all, it is important that each individual connector be connected only to its intended receptacle. While color coding and various types of indicia are helpful in this respect, they do not preclude error. It is therefore highly desirable that means be provided making it physically impossible to mate a connector with any receptacle other than its intended receptacle. Secondly, it is frequently important, both to protect the equipment and as a safety factor, to connect and disconnect a series of connectors to and from a panel in a particular order. For example, where a ground is used, it is generally desirable that the ground makes first and breaks last.
Prior art workers have devised electrical panel assemblies wherein means are provided to prevent mating of a contact with other than its intended receptacle and means requiring the connectors to be mated with their respective receptacles in a given order, and disconnected therefrom in the reverse order.
An exemplary electrical panel assembly of the type contemplated is taught in U.S. Pat. No. 4,767,347. The teachings of this patent are incorporated herein by reference.
Briefly, U.S. Pat. No. 4,767,347 describes an electrical panel assembly having a plurality of receptacles for use with single contact cable connectors. The connectors and receptacles are of the well-known type having single contacts which lock together when the connector is mated with the receptacle and rotated a partial revolution with respect thereto. The panel assembly comprises a front panel element having two or more receptacles mounted therebehind in side-by-side relationship. In an exemplary embodiment, the panel was described as having a ground receptacle, a neutral receptacle, and first, second and third current-carrying receptacles, arranged in that order. The front panel element has an opening therein for each receptacle through which a cable connector can be extended for mating with the receptacle. Polarizing devices are provided in association with each receptacle and in association with each cable connector, to assure that each cable connector can be mated only with its respective receptacle. Each front panel element opening, except for the first opening for the ground receptacle, is provided with a locking mechanism shiftable between a normal locking position wherein it precludes entrance of a connector into its respective front panel element opening and a retracted position, permitting entrance of a connector into its respective front panel element opening. The locking mechanism for each front panel element opening is shifted to its retracted position when the appropriate connector is inserted through the preceding front panel element opening and mated and locked with its receptacle. Each locking mechanism in retracted position precludes removal of the connector from the preceding front panel element opening. As a result, the ground, neutral, and first, second and third connectors must be connected to the panel assembly in that order, and can only be disconnected therefrom in the reverse order.
In the preferred embodiment of U.S. Pat. No. 4,767,347, the front panel element has a receptacle housing mounted to the rear surface thereof behind each of the front panel element openings. Each front panel element opening is provided with a cover, biased to the closed position. Each receptacle housing is provided with a locking pin which normally engages and locks the cover of the next succeeding front panel element opening in closed position. The receptacle housing contains a latch which normally locks the locking pin in its locking position. Each connector is provided with a polarizing shell and each housing is provided with a mating polarizing ring so that each connector can be connected only with its intended receptacle. When the first or ground connector is connected and locked with its respective receptacle, its polarizing ring shifts the latch to an inactive position releasing the locking pin so that the next front panel element cover can now be opened and its respective connector can now be mated with its appropriate receptacle. When each front panel element cover is released and opened in this way, it maintains its respective locking pin in unlocking position. This, in turn, prevents removal of the preceding connector from the panel assembly. Thus, the connectors must be connected to their respective receptacles in a given order and can be disconnected only in the reverse of that order.
The panel of the present invention constitutes an improvement upon the prior art panel just described. The electrical panel assembly of the present invention is simpler in construction, requiring fewer parts. As a result, it is easier and quicker to assemble, and cheaper to manufacture. The overall size of the electrical panel assembly may be made smaller and may be made to accommodate smaller connectors.